Let me start off by saying that I have owned at least 3-4 betta's before when I was much younger (12-14ish). Needless to say, I remember them dying pretty early. My parents were never much into fish care.

Now that I'm much older (19) with a job, I can afford proper care for many new animals. I want to get into fish again, as my only other pet is a Siberian Husky who is my best friend. I figured I would start out slow with a Betta or Goldfish, but Bettas are much more attractive to me.

What I am looking for is the following:

Tank & Size (Petsmart/Petco/Wal-Mart availability if possible) Also looking only to keep the Betta in the tank, so I would prefer it to not be so big.
Heater!! (Brand name and store, if possible). This is probably the most important thing to me right now.
Thermometers (Brand/store)
Food (Brand)
Water Conditioner (Brand)
Live Plant types (I really dislike fake plants, but I am unsure of how much care is needed for live ones in a tank.)
Gravel/Sand (if any)
Filter (Brand/Store) if any.

And lastly, what to look for when buying a Betta. Most of the ones I've seen in my lifetime are kept in really, really small bowls, or plastic cups(how cruel...) But those are the only containers I have ever seen them in. I'm unsure if I'm ever going to find different living conditions.

I need to know how a healthy looking Betta acts and looks as I have NO idea.

If there is anything critical I forgot, then please inform me.
I live in Colorado, where it's still very cold right now. That is why I am putting emphasis on a great heater.

I live in Scotland, where we don't have the stores you mentioned so i can't guarantee availability but I'll give you a few pointers:

Tank & Size (Petsmart/Petco/Wal-Mart availability if possible)

5g minimum size for a betta on it's own. Some say 2.5g but personally I think this is just too small. Larger tanks are a little more forgiving with paramaters also. I know you only want the betta for now, but if you plan on ever adding more fish then you will need a bigger tank. A 30g is a great starting tank size - not too big, but big enough to give a bit of choice when it comes to stocking. If you're sure that you just want the betta then 5g would be ideal.

heater!!

For a 5g tank a 25W heater will be plenty. This is a pretty standard sized heater so should be available pretty much anywhere that sells fish.

Thermometers

Go for an internal thermometer. brand and store really isn't important. They're all the same as far as i can see. the sticky ones for outside of the tank give something inbetween tank and room temp, whereas the little internal ones that have a suction cup are more accurate, and only cost £1 or so.

Food

Flakes or pellets (many feed hikari betta pellets) is a good staple diet. Once a week, to vary it a bit and keep your fish in good health feed a meaty food like froxen bloodworm or brineshrimp, and again once a week some shelled froxen peas (defrosted) to help prevent bloating and constipation.

Water Conditioner

I use API Stress Coat. Any dechlorinator should do though.

Live Plant types

Depends entirely on your lighting. Bettas usually enjoy floating plants like elodea to play with. Others would be crypts, jave moss, jave fern etc but again this depends on your lighting.

(Gravel/Sand (if any)

This is entirely down to your personal taste. Your betta won't mind at all. if you're going for planted live plants then a pea sized gravel is usually best. if you wanted to go for heavy planting thn eco complete is probably the best plant-substrate you'll find but it is very expensive and i find that regular pea sized gravel does fine with most plants.

Filter (Brand/Store) if any.

I use Elite Stingray 5. Filters are necessary, but bettas don't like strong currents. I find this one (rated for 5g) has a soft enough output not to stress the fish and since you would be keeping a betta alone then the bioloqad wouldn't be too high and this, in the absence of overfeeding, would be plenty. If you did decide to go for a bigger tank in order to have more fish later on then i find the fluval 2+/3+/4+ filters are quite good to start off with. they have variable outputs so you can adjust it to make it soft enough for your betta. They're easy to maintain and are popular so getting aditional media shouldn't be a problem, and they have a wee clogging indicator thing which I think could be useful for anyone new and not sure exactly how to maintain a filter. I use the 4+ in my community, and aside from the points i already mentioned I do actually think it's a good wee filter.

Tank and Size - Alright, I think I'll go with a 5 gallon one then. Would any regular glass fish tank do? I don't know if they sell those aquarium kits where you live, but here, they have whole kits that come with filters and lights. I need to know if I should look into one of those, or customize my own. Whatever is best for the fish.

Heater - Alright, great. Do they sell ones that have a constant 78 degrees temperature?

Thermometers - How tiny are they? I remember we used to have a sticker one that didn't work very well, and it was really tiny. Wouldn't one with a suction cup kinda, I dunno, ruin the view?

Food - Okay, pretty standard. A question about the meaty foods though. You said FROZEN bloodworms or brineshrimp. Do you keep those in a freezer after purchase? Or are you talking about freeze dried food? Also, peas? I couldn't see a betta eating a whole unthawed pea. I'm assuming you dice it up, or mush it into tiny betta fish bites? Or would I let the pea float at the water's surface and let him pick at it?

Water Conditioner - No question here. Are you aware of the Nutrafin Betta Plus water conditioner? Is it a good brand? I actually have a bottle of that.

Live Plants - Okay, biggest question here. Would I have to research these underwater plants before associating them with a fish? Seriously. I have about 4 live house plants and know nothing about water based plants. I see big problems cropping up when you clean the cage. Wouldn't it harm the plant? Also, I don't know what you mean by lighting. I have a normal room light, though my window is wide open (to let sun in) during the day. It lights the room fairly well. Would I have to invest in some UV lamp that sits over the fish tank or something to let the plants thrive?

Gravel - Would pea sized polished rocks work out good? I want something that plants live in well. Like I said, I know nothing about underwater plants.

Filter - Whoa, that stingray filter looks like something out of a sci-fi movie. It looks a little big for a 5 gallon tank though. Is the one you're recommending to me suitable for a 5 gallon tank (size wise?)

Glass thermometers wouldn't ruin the view, some people actually think it's cool :p use one with a suction cup so u can hide it in a corner if you want to.

For food, Ocean Nutrition's betta products are great. ON Atison's betta food is good for staple food. While ON Atison's betta pro is excellent for conditioning. Hikari Bio-gold is very good too. These products, I find, is readily accepted by all bettas. Not like other food some pet stores carry.

Water conditioner I also use API Stress Coat, wonderful.

Live plants will require lighting other than your room light, unless you plan to put it outside. They require around 10 hrs of light a day. If you are a beginner, I don't recommend it. As if you could not take care of it properly, it will just end up polluting your tank.

Gravel has pros and cons. some bettas freak out when they see their reflection on the tank floor, gravel will help with this. Gravel may also make you think that the tank is sparkly clean but in truth, all the dirt is trapped in it. Gravel can also be a good place for the benificial bacteria to grow it, which is good for you. But if it gets too dirty, be ready with your fish medicine as this can make him sick easily.

While you are looking at aquarium kits with light hood and all, keep in mind that for plants you will need at least 10W of fluorescent light. A way to get there without a lot of expense is to get an incandescent hood and then get a screw in fluorescent bulb. They have one with u shaped tubes in the pet area at Walmart. Otherwise you will be looking for custom lighting kits elsewhere such as at AHSupply, on line, to fit into your existing light fixture. I am doing that right now.
For the lower light levels you can get without excessive efforts, the only plants you can grow will be marked as low light plants. They include both common types of java fern and java moss. For a betta, I would lean toward the java ferns since java moss is mostly good hiding places for fry but you won't need that. The java fern comes in a version that has long broad leaves and one that is similar but has a lot of splitting toward the end of the leaf, sort of little leaflets. Do not plant the java fern root crown, it will kill the plant. Instead tie it to something like the decorative wood things they sell and let the roots reach down to the nearby gravel on their own.
Before you start, make sure you read the threads on cycling your tank. If you were trying to keep a betta in a bowl there would not be much point to it since it is all new water every day or two and not pants or decoratins to hold the nitrifying bacteria. In a real tank, it can be the primary difference in how long your betta will live.

Heater: Hydor makes the Theo brand which seems to work pretty good, plus has an indicator light that tells you when its on and it's decently priced. You still need a thermometer (oh well :) )

Tank: For just one fish probably one of those 5 gallon Mini-Bows might be a good tank. It comes with a filter too(Whisper InTank). The only thing is that it's got an incandescent light but I've never really had an issue with temps. If you eventually want more than one fish I'd just do a setup with one of those plain tanks and the equipment that you want. It generally works out to be cheaper anyways. I'll recommend http://www.drsfostersmith.com/product/shop.cfm?c=3578 for your equipment.

Frozen stuff: Keep it in the freezer and then either thaw it, deshell it, and squish it (peas) or hack off a chunk (bloodworm cubes) and either plunk it in the tank or let it thaw and feed it then (I do this because then I can control the "juices" that get into the tank).

I agree about reading up on cycling. This is something that is commonly not researched first (I made the mistake with my first tank too) and then there's people going "oops".

As for looking for a healthy Betta, if you can find some kind of breeder or mom & pop store (I know you said you were limited but sometimes you can find an LFS where you'd least expect it) that sells them you may be better off. Try to avoid the ones that are laying on the bottom of the cups, they're probably beyond help. Don't give in to dirty nasty Betta bowls because it sends the message that it's ok to treat them like that.

And lastly, I'd like to say Welcome to the Fishforum! It's great to see people coming here for advice on how to do things correctly!!!!

I've got my show betta in a 5.5 gallon planted with a 12 watt strip. 25 watt heater (all glass), Duetto 50 filter with the carbon removed and a second sponge added. Sometimes I put some peat granules between the sponges. Plants: Right now mostly Rotala indica with a couple of sprigs of Ludwegia repens and a big wad of floating Riccia fluitans and some java moss. I have plain black spectrastone gravel with a little bit of fluorite mixed in, but ih I were doing it again, I would ise ecocomplete or onyx or fluorite black sand or organic potting soil mixed with some peat (The stuff they sell for bonai is great). From there, you can pretty much do whatever plant wise. Skip the strip light and get a 23 watt CF desk lamp if you prefer (if you get the right one it's a really nice look) and you'll expand the possibilities to growing a lawn in there with sags or hairgrass or glosso or HC.

Now, I also have a couple of ADFs and a Mystery snail in with mine as a janitorial crew (and to force me to feed something other than betta pellets - they're too easy.)